The inventive concept relates to a semiconductor memory device, a semiconductor memory system including the same, and a method of verifying the system, and more particularly, to a semiconductor memory device whose reliability and performance are improved by controlling an initial voltage level when performing verification operations, and a semiconductor memory system including the device.
When a verification operation is performed with respect to a programmed state generated according to each piece of data programmed into memory cells in a semiconductor memory device and a semiconductor memory system, a setup operation of a verification voltage corresponding to the programmed state is initiated. In other words, the setup operation indicates an operation of converting the verification voltages from a first level to a second level. An amount of time necessary for a setup operation of word lines varies depending on whether or not a verification of the programmed states is complete. This causes a time taken for the setup operation of word lines to vary according to the programmed states, leads to deterioration of the semiconductor memory device and the semiconductor memory system including the device, and thus decreases reliability of program data.